David Cameron faces another bitter battle over his plans to introduce gay
marriage, with more than half of Conservative peers expected to vote against
the move.

Dozens of Labour, Liberal Democrat and crossbench peers are also expected to vote against the Bill, threatening the Prime Minister’s plans for the first homosexual marriages to be held early next year.

Some Lords believe peers will table hundreds of amendments, with so-called “backwoodsmen” flocking to the Lords to “filibuster” in a bid to delay the legislation.

Details of the brewing rebellion in the Upper House emerge just days after the Commons vote on same-sex marriage. The Bill was passed but more Tory MPs voted against than in favour.

Michael Fallon, one of just 10 ministers who voted against the Bill, spells out his reasons for doing so in an interview with The Sunday Telegraph today.

The business minister suggests the move was railroaded through without a wide enough consultation. He said: “I didn’t think you could redefine something that is so central as marriage without much wider not least from those who are married and prize the status of marriage.”

Mr Fallon, however, said last week’s debate offered MPs a “genuine free vote” and adds: “That’s over now. The Commons majority was decisive and we have to accept that.”

His constituents in Sevenoaks, Kent, are “overwhelmingly opposed” to the measure, Mr Fallon said.

Mr Cameron has shown himself to be a passionate supporter of same-sex marriage, arguing that the policy is in keeping with Conservative values, even though it did not feature in the party’s 2010 election manifesto. Lib Dems in the Coalition have tried to claim the policy as their own.

The Coalition Bill to introduce same-sex unions is expected to reach the Lords in May after it has been scrutinised at the Commons committee stage.

Lord Lawson of Blaby, the Conservative peer and former chancellor, said he did not accept that gay people suffer from discrimination and expects to vote against the Bill when it reaches the Lords.

“Discrimination did exist before but it was ended by the introduction of civil partnerships,” Lord Lawson said.

“I was perfectly happy with that, but what we have now is a question of the redefinition of marriage. I do not believe the case for that has been made.”

Fellow Conservative peers opposed to homosexual weddings include Lord Waddington, a former home secretary, Baron Cormack, a former deputy leader of the House of Commons, Lord Mackay, the former lord chancellor, and Baroness O’Cathain, a respected businesswoman who has served on the boards of British Airways and Tesco.

One Tory whip in the Lords said: “I expect more than half of Conservative whips will vote against. I think many of the old guard of Labour peers will do the same. Liberal Democrats peers may also do so and who knows what we will see with the cross-benchers.

“It would have been better for Mr Cameron if he had tried to push this through a year or two ago - before Lords’ developed a taste for rebelling.”

Lord Hodgson, a Conservative peer who will vote in favour, also expects around half of his party colleagues will oppose the plans.

While some Tory peers object to gay marriage on religious grounds, others claim that the Bill is a “distraction” from addressing the economic crisis and that there is little appetite amongst the general public – or even gay people – for the change.

“The Prime Minister has just decided on a whim that this is necessary,” one Conservative peer said. “He apparently thinks I have no idea what is going on in the country… I think I have a hell of a lot more of an idea that is going on in the country than he does.

“The public were assured by the Labour government that civil partnerships would not slip into gay marriage. But there you are: don’t put your faith in politicians.”

In the Commons vote last Tuesday, 139 Conservative MPs voted against the Bill and 132 voted in favour.

Twenty-two Labour members and four Lib Dems also opposed the legislation. However, most peers suspect that significantly more Labour and Lib Dem will oppose the Bill when it reaches the Lords in the spring.

Lord Stoddart, the independent Labour peer, said that it was “completely and utterly unnecessary” for the Prime Minister to introduce gay marriage, especially while many of the country’s economic problems remain unsolved.

“Marriage was devised a long time ago to protect women and children – to tie the male to the family so that the children could be brought up and protected by two loving parents,” the peer said. “That does not really apply in the case of homosexuals.

“I am sure that there will be many amendments and it is possible that the House of Lords will throw it out. To get this through by the end of the year is very unlikely.”

Lord Stoddart said he was “absolutely certain” that there are many Labour lords who will support amendments that will “help to modify, if not destroy, the Bill”.

Lord Tyler, the Lib Dem peer, believes that many “backwoodsmen” – the term to describe peers who rarely attend parliament – will make efforts to scupper the legislation by “pontificating”, filibustering and tabling many amendments.

“Be prepared for a long slog and some long nights,” said Lord Tyler, who will vote in favour. “I would be amazed if the Government keeps to its timetable on this.”

Other members of the House of Lords known to oppose gay marriage include Lord Carey, the former archbishop of Canterbury, and the crossbenchers Lord Curry, Lord Tombs and Lord Singh.

Gay marriage has exposed strong divisions at all levels of the Conservative Party. Last weekend 25 Conservative association chairman and former chairman wrote to Mr Cameron to warn the Prime Minister that members and donors are abandoning the party over the issue.

However, Lord Deben, who as John Gummer served as a Tory minister and the party’s chairman, attacked the “inconsistency” of those Conservatives who voted against the Bill in the Commons. He plans to vote in favour when the legislation reaches the Lords.

“If you believe in fidelity and permanence it seems an odd thing not to encourage people to celebrate that,” Lord Gummer said.

“Science has taught us that some people have this attraction and don’t have heterosexual attraction. This is now universally agreed and so it is the right thing to do for society to acknowledge that.”

He added: “I find it very difficult to listen to the inconsistency of people who themselves have been several times married now standing up in the House of Commons and defending the sanctity of marriage.”

Lord Deben also criticised free-market Tories who held libertarian views “on all other matters”, but made an exception on gay marriage.

“That doesn’t seem very logical to me,” he said. “This is a libertarian issue.”